For the price of a single 1070 I can get two 970, so the ratio hashrate/dollar is better with the 970. Since the power consumption is my lowest concern that may be good. Also, I have just a little spare money, just enough to buy one 970.
remember that power consumption mean also more power from psu = more costly psu, more cooling needed etc, it's not about electricity cost only....
I have a beefy 1000W PSU. All the components already have been ordered and received up to a month ago. The GPUs are running in my basement, so there's no big problem of cooling. Given all of these advantages, it is a good idea ? You're the reference in NVidia mining for me, so I'd like to get your thought on this.